A light of intense photographic power is produced by burning bisulphide of carbon in an argand lamp and passing a stream of nitric oxide through the centre of the flame Nitric oxide is easily produced as wanted by allowing nitric acid to act on scraps of copper.

The following specific directions will enable the reader to produce this light in a less simple but more effective manner: A quart bottle with a somewhat large mouth, has a cork with two openings. Through one of these a tube passes to near the bottom of the bottle; through the second a large tube packed with iron scale issues. Fragments of pumice fill the bottle, and on these carbon disulphide is poured. A current of nitric oxide gas, prepared by Deville's method - by the action of nitric and sulphuric acids on metallic iron contained in a self-regulating reservoir - is passed through the bottle, where it takes up the vapor of the disulphide. It is then led through the safety-tube, packed with iron-scale, to a gas burner of the required capacity Excellent photographs have been taken in five seconds with this light, the object being six feet distant. In photographic power the light is asserted to be superior to the magnesium or calcium light, and even to surpass the electric light itself. The products of combustion are noxious and must be gotten rid of.